Wednesday, September 21, 2016

The simplicity of the non-catalytic stove makes it the
most popular type of stove in North America by far.With most non-cats, the consumer only needs
to worry about a single lever to regulate the amount of air in the
firebox.But some consumers unwittingly
buy a very unique kind of non-cat, a downdraft stove, and often regret it.

Today there are only a handful of downdraft stoves on the
market, Most have been pushed aside by non-cat stoves with air tubes that
reburn smoke as it exits the firebox.The downdraft stove works with a second lever that engages a by-pass
damper which forces the smoke down into a chamber where heat can reburn it
before it goes back up the chimney.

Almost all stoves on the market today do not try to get smoke
to go down, but rather try to reburn it on its journey upward with secondary
air introduced through holes in tubes or in upper wall of stove – or with a
catalyst. Hybrids use both tubes to inject for secondary air and a catalyst. (Click here for more on cat, non-cat and hybrid stoves.)

Downdraft stoves tend to be finicky, need to be very hot to
work properly and are more prone to leaking smoke into the house.Most consumers should not consider them
unless they know what they are getting into and are prepared to be much more engaged
with their stove.The same can be said
about catalytic stoves.Consumers should
understand that they need to know how to use the second lever that engages the
by-pass damper and occasionally check the catalyst, and replace it when it needs replacing.

Stove change out programs, that switch out old stoves with new,
EPA certified models may want to exclude downdraft stoves from eligible
replacements as they may be the hardest class of stove to run consistently without
visible smoke.

The downdraft stove became popular in the 1980s when Vermont
Castings used it to extract more heat from a stove and to help pass the
emission testing required by the state of Oregon, and later by the EPA. The by-pass damper helped slow down the fire,
create turbulence, and extract more heat from the hot gases before they went up
the stack. The Resolute Acclaim, one of the most popular wood stoves of the last
century, was a downdraft stove.It
clocked in at 3.4 grams per hour and continued selling through the 2000s, but
has since been taken out of production.

Today, there are a handful of downdraft stoves on the
market. The Harman
TL300 is a downdrafter and Vermont Castings still has one or two. The Lopi Leyden and the Avalon Arbor (same stove) went off the market in 2012. (We had written that they were still on the market, but a reader corrected us.) There may be better designs of downdraft stoves that are easier to operate in other countries.

The original Frankin stove
was a downdraft with no
front door and often
made for a smoky house.

Downdraft stoves have existed for centuries in various
designs. The original stove invented by Ben Franklin also had a downdraft
incorporated into the design, and it is one of the reasons that the stove was
so finicky and disfavored by the majority of consumers. Franklin himself admitted
that the stove was difficult to operate and took lots of attention and wasn’t
something that “could be left to the servants.” Later iterations of the Franklin stove added a door and most got rid of the downdraft.

Consumer feedback

Hearth.com
is a premier chat room for wood stove experts and rookies alike. It contains a
lot of good feedback on downdraft stoves:

- “The
creosote smell when closing the bypass is not an uncommon issue with the
downdrafting stoves. I've seen Harman stove owners complain with it as well. I
will sometimes get it. Sometimes not. It's not noxious, just a faint odor that
I can do without. CO monitor pays it no mind.”

- “I
wish a group of downdrafters could get their heads together on this one and
figure out what is going on. It's a common problem to different stoves. Maybe
that box full of smoke is letting some escape at the joints.”

- “I've
smelled it when the draft was strong, but typically it comes when the flue has
begun to cool down a little. Loading lid was a prime suspect, but I regasketed
it and sat a cast iron pot on there.”

- “Downdraft
stoves are notoriously fussy and demanding of a strong draft.”

- “The
Leyden has undergone a few changes of the years. There are some ports that need
thorough cleaning "Monthly" as well and they are not easy to reach. Make
sure these ports are cleaned regularly. Your manual shows how to do this
correctly.”

- “These
stoves have to be seriously hot to work.”

- “I
sometimes get a bit of smoke when loading. Mostly because I'm too lazy to do it
right. Again, operate the stove as designed and if it doesn't work, get a look
at the flue, check for ash buildup, etc.. ... your flue design is gonna be a
tough one.”

- “I
don't want to melt your stove down, but my hunch is that you're not getting it
hot enough on a 3-4" coal bed.”

- “Is
the wood very well seasoned? That is very important with this stove as is a
good draft.”

- “I
would try running your stove top temperature a little higher (650-700) before
you go to secondary burn, typically you get some drop in stovetop temperature
when you close the damper.”

- “I
also suggest to take off the Vermont Castings Resolute and Lopi Leyden. Both
use a different mechanism to achieve a clean burn than the other non-catalytic
stoves. Both stoves usually have a steeper learning curve, can be prone to
costly repairs and are better suited for full-time burners which does not seem
to be your intention.”

- “As
others have mentioned, the Oakwood (and other downdrafts like Lopi Leyden and
certain Vermont Castings models) can be a bit fussy about dry wood and good
draft, requires a bit more babysitting and longer learning curve, and is not
well suited to slower/lower burns in months like November and April.”

- “You
want a stove with tubes in the top or a catalyst. Avoid stoves that draw smoke
down into the back of the stove. For example: Vermont Castings, some Harman's
and Lopi Leyden.”